- Unix, Linux Command

NAME

SYNOPSIS

DESCRIPTION

The cipherlist command converts OpenSSL cipher lists into ordered
SSL cipher preference lists. It can be used as a test tool to determine
the appropriate cipherlist.

COMMAND OPTIONS

Tag

Description

-v

verbose option. List ciphers with a complete description of
protocol version (SSLv2 or SSLv3; the latter includes TLS), key exchange,
authentication, encryption and mac algorithms used along with any key size
restrictions and whether the algorithm is classed as an export cipher.
Note that without the -v option, ciphers may seem to appear twice
in a cipher list; this is when similar ciphers are available for
SSL v2 and for SSL v3/TLS v1.

-ssl3

only include SSL v3 ciphers.

-ssl2

only include SSL v2 ciphers.

-tls1

only include TLS v1 ciphers.

-h, -?

print a brief usage message.

cipherlist

a cipher list to convert to a cipher preference list. If it is not included
then the default cipher list will be used. The format is described below.

CIPHER LIST FORMAT

The cipher list consists of one or more cipher strings separated by colons.
Commas or spaces are also acceptable separators but colons are normally used.

The actual cipher string can take several different forms.

It can consist of a single cipher suite such as RC4-SHA.

It can represent a list of cipher suites containing a certain algorithm, or
cipher suites of a certain type. For example SHA1 represents all ciphers
suites using the digest algorithm SHA1 and SSLv3 represents all SSL v3
algorithms.

Lists of cipher suites can be combined in a single cipher string using the
+ character. This is used as a logical and operation. For example
SHA1+DES represents all cipher suites containing the SHA1and the DES
algorithms.

Each cipher string can be optionally preceded by the characters !,
- or +.

If ! is used then the ciphers are permanently deleted from the list.
The ciphers deleted can never reappear in the list even if they are
explicitly stated.

If - is used then the ciphers are deleted from the list, but some or
all of the ciphers can be added again by later options.

If + is used then the ciphers are moved to the end of the list. This
option doesnt add any new ciphers it just moves matching existing ones.

If none of these characters is present then the string is just interpreted
as a list of ciphers to be appended to the current preference list. If the
list includes any ciphers already present they will be ignored: that is they
will not moved to the end of the list.

Additionally the cipher string @STRENGTH can be used at any point to sort
the current cipher list in order of encryption algorithm key length.

CIPHER STRINGS

The following is a list of all permitted cipher strings and their meanings.

Tag

Description

DEFAULT

the default cipher list. This is determined at compile time and is normally
AES:ALL:!aNULL:!eNULL:+RC4:@STRENGTH. This must be the first cipher string
specified.

COMPLEMENTOFDEFAULT

the ciphers included in ALL, but not enabled by default. Currently
this is ADH. Note that this rule does not cover eNULL, which is
not included by ALL (use COMPLEMENTOFALL if necessary).

ALL

all ciphers suites except the eNULL ciphers which must be explicitly enabled.

COMPLEMENTOFALL

the cipher suites not enabled by ALL, currently being eNULL.

HIGH

high encryption cipher suites. This currently means those with key lengths larger
than 128 bits, and some cipher suites with 128-bit keys.

MEDIUM

medium encryption cipher suites, currently some of those using 128 bit encryption.

CIPHER SUITE NAMES

The following lists give the SSL or TLS cipher suites names from the
relevant specification and their OpenSSL equivalents. It should be noted,
that several cipher suite names do not include the authentication used,
e.g. DES-CBC3-SHA. In these cases, RSA authentication is used.

Camellia ciphersuites from RFC4132, extending TLS v1.0

TLS_DH_DSS_WITH_CAMELLIA_128_CBC_SHA Not implemented.
TLS_DH_DSS_WITH_CAMELLIA_256_CBC_SHA Not implemented.
TLS_DH_RSA_WITH_CAMELLIA_128_CBC_SHA Not implemented.
TLS_DH_RSA_WITH_CAMELLIA_256_CBC_SHA Not implemented.